Modern telecommunication standards often require a simultaneous transmission and reception of signals. For example, the third generation communication standard Wideband CDMA/UMTS (Wideband Code Division Multiple Access, Universal Mobile Telecommunication System) uses a frequency division duplex (FDD) method to transmit continuous signals while receiving signals on a different center frequency simultaneously. According to the specification of the UMTS standard a total number of at least nine different operating bands are specified. In each operating band, a first frequency range is specified for transmitting signals by a user device to be received by a base station. Concurrently, a second frequency range is specified for the base station. The transmitted signals are received by the user device. Because the specification requires a good signal quality for an error-free signal reception, it is necessary to suppress any interfering signal coming from an external source or from simultaneous transmitted signals sufficiently. It is also expected that more frequency operating bands will be added into existing communication standards or new standards with new operating bands will be specified in the future.